That's the ebay templating system, right? Has been around for almost 10 years, but never gained that much traction.
It definitely has not gained a lot of traction outside of ebay but there is a fair amount of buzz around the marko6 release with a completely new tags-based language.
It is also one of the few frameworks that leverage html streaming in a simple way (and has for a long time) and offers islands-style partial hydration out of the box.